Lessons Learned from the Construction, Inspection, and Defect Assessment of Reinforced Concrete Foundations for Wind Turbines

Abstract

Foundations of wind turbines are subject to challenging conditions during their service life as they support ever larger wind turbines under complex loading situations. There have been numerous reports of cracked concrete foundations of wind turbines. Cracking can impair the durability and serviceability of the foundations, thereby leading to very expensive repairs or even to premature failure of the structure. To avoid cracking-related problems and improve the quality of concrete foundations, it is important to gather information and experience from the production stage and its outcome. However, although problems and defects in the construction of wind turbine foundations are widespread, they have very seldom been documented and reported, in particular from a contractor’s perspective. This article analyses and critically reviews data collected during the production, inspection, diagnosis, and repair activities conducted in relation to the construction of foundations for a wind farm project in Sweden. The extent of defects observed on individual foundations is assessed and used to investigate the eventual relation between the observed deviations and different production aspects. Investigation methods to determine the importance of these defects and their consequences and possible remediation measures are also discussed. Finally, recommendations are proposed to improve the quality control of wind turbine foundations.